1. Field of the Invention
The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus for altering brightness of images.
2. Description of the Related Art
Conventional image pick-up apparatuses such as digital cameras, have a gradation correcting function for correcting a gradation of an picked up image. Using this gradation correcting function, an image can be obtained of a more clear object than the original picked up image.
A patent document 1 discloses a digital camera provided with the gradation correcting function. The digital camera disclosed in the patent document 1 displays a through image (a live view image) on a touch panel LCD, allowing a user to touch a position in a main object seen in the displayed thorough image to designate a certain area of the through image, and adjusts a gradation altering characteristic in a luminance range of a gamma correction for correcting an image signal expressing the designated certain area of the through image, thereby adjusting brightness of the main object seen in the through image. The digital camera disclosed in the patent document 1 allows the user to touch and designate a position in the main object of the picked up image to make brighter a predetermined area in the main object of the picked up image.
A patent document 2 discloses an image pickup apparatus, which changes a gradient assignment ratio to concentrate a gradient on a face portion and/or focused portion in an picked up image. The image pickup apparatus disclosed by the patent document 2 can change a brightness level at the face portion and/or focused portion seen in the picked up image, making the face portion and/or focused portion more clear.
The patent document 1 is Japanese Patent No. 2006-50085 A, and the patent document 2 is Japanese Patent No. 2008-118383 A.
The digital camera disclosed in the patent document 1 can correct a brightness level of only the predetermined area including the position in the through image touched and designated by the user. Therefore, in the case that the user wants to correct the brightness level of the whole area of the main object, the user is required to repeatedly perform troublesome operations, touching the through image several times to designate the whole area of the main object.
In the image pickup apparatus disclosed in the patent document 2, the area whose luminance level is to be changed is previously determined. Therefore, the image pickup apparatus has a disadvantage that cannot correct the brightness level of an area(s) other than the area previously determined.
The present invention has an object to provide an apparatus which can easily alter luminance levels of arbitrary areas of a picked up image.